Composition board made from material pretreated with a fluxed water repellent



United States Patent :"lice 3,410,813 Patented Nov. 12, 1968 3,410,813COMPOSITION BOARD MADE FROM MATE- RIAL PRETREATED WITH A FLUXED WATERREPELLENT Y Craig C. Campbell, John W. Schick, and John H. Stockinger,Cherry Hill, N.J., assignors to Mobil Oil Corporation, a corporation ofNew York No Drawing. Continuation-impart of application Ser. No.397,267, Sept. 17, 1964, which is a continuation-in-part of applicationSer. No. 316,505, Oct. 16, 1963. This application Mar. 30, 1966, Ser.No. 538,612

12 Claims. (Cl. 26017.2)

ABSTRACT OF THE DISCLOSURE Composition boards are formed from fibers,particles, and mixtures of fibers and particles that have beenpretreated with a water-repellent material. The fibers and/ orparticles, generally cellulosic, are coated with waterrepellent materialsuch as wax emulsion and then heated to flux the water-repellentmaterial over the particle surface. A catalyst for a thermosetting resincan also be placed on the particle surfaces. Then the pretreatedparticles and/or fibers are admixed with a thermosetting resin, moldedto form composition board, and heated to thermoset the thermosettingresin.

Composition Board This application is a continuation-in-part ofcopending application Ser. No. 397,267, filed Sept. 17, 1964, nowabandoned, which in turn is a continuation-in-part of application Ser.No. 316,505, filed Oct. 16, 1963, now abandoned.

This invention is concerned with composition boards made from particlesand/ or fibers bonded with a thermoset resin, and to a method forproducing such composition boards. It is more particularly concernedwith composition boards containing particulate or fibrous material, orboth, bonded with a thermoset resin and having high bond strength andenhanced resistance to water, and to a method for producing suchcomposition boards.

As is well known to those familiar with the art, a wide variety ofcomposition boards have been produced by bonding compositionboard-forming materials with suitable binders. Such boards include chipboard, particle board, and fiber-board. In this specification and theclaims, composition board-forming materials are materials such asfibers, particles, and mixtures of fibers and particles. The termsfibers and particles encompass a wide variety of materials of mineraland vegetable origin, and synthetic organic fibers like Dacron andnylon. Typical minerals from which such board-forming materials can bemade include gypsum, asbestos, fiberglass, and the like. Generally,however, composition boards are made by bonding fibers and/or particlesof vegetable origin, usually cellulosic materials, into desiredconfigurations. The term cellulosic, as used herein, is embracive ofvarious plants and trees that contain the lignocellulosic complex.Within the term cellulosic materials, therefore, as used herein, arecontemplated fibers, chips, shavings, sawdust, and the like derived fromvarious plants and trees, including hard woods, soft woods, cotton,bagasse, kenaf, hemp, and jute.

A variety of materials have been proposed for use as binders for fibersand particles. Materials that can be thermoset to provide an infusiblebinder, i.e., thermosetting resins, lending greater strength anddurability to the bonded products are highly desirable.Phenolformaldehyde, urea-formaldehyde, and melamine-formaldehyde resinsare among the numerous thermosettin g resins that have been proposed forsuch uses.

In the manufacture of composition boards with a thermosetting resin, theresin is generally mixed with a solvent for application to theparticulate or fibrous board forming material as a solution or apaste-like slurry. Accordingly, the viscosity of the resin can be animportant factor in such uses. If the resin is too thin, there will be atendency for it to penetrate into the pores of the fibers or particlesbeing bonded, particularly when subjected to a high cure temperature. Bysuch penetration, resin will be removed from the glue line at which theparticles of fibers are bonded, resulting in a starved glue line havingpoor bond strength. This was particularly apparent in tests involvingketone-aldehyde resins. A water solution of an acetone-formaldehyderesin, for example, should have a Gardner-Holt viscosity (ASTM Dl545 60)at ambient temperatures of at least 5 seconds to avoid excessivepenetration of the pores and substandard bond strength. Even when resinsof lower viscosity are applied together with a wax emulsion (a standardpractice to increase water resistance of composition boards), bondstrength and water resistance of the board are generally substandard.

When composition boards are made from vegetable fibers, particularlybagasse, it has been found necessary to remove the pith. Pith is thesoft central portion of the stalk, which contains short fiber andresidual sugars. Conventional methods for bagasse processing requiredepithing, since by conventional standards the short fiber pith causeshigh water absorption and contributes nothing to the strength of theboard. The depithing operation results in a loss of, reportedly, 30-50%of the bagasse. More significantly, depithing operations are relativelyexpensive. Typical depithing methods are described, for example, in NewDevelopments in Sugar Cane Bagasse Pulping by Joseph E. Atcheson, PaperTrade Journal, pages 30-36, May 13, 1963. It will be appreciated that,if composition boards could be made from raw bagasse, i.e., bagasse thathas not been depithed, there would be significant savings from theelimination of depithing cost and complete utilization of the bagasse.

It has now been found that composition boards having improved bondstrength and water resistance can be produced simply and economically.It has been discovered that such improved composition boards can bemade, provided that the fibers and particles used in their manufactureare pretreated with wax or other water repellent material, as describedhereinafter. It has also been discovered, in accordance with thisinvention, that composition boards can be successfully prepared from rawbagasse.

Accordingly, it is a broad object of this invention to provide improvedcomposition boards. Another object is to provide composition boards withenhanced water-resistance. A specific object is to provide compositionboards made with thermosetting resin binders, that have increased bondstrength and enhance water resistance. Another specific object is toprovide such composition boards made from raw bagasse. Other objects andadvantages of this invention will become apparent to those skilled inthe art, from the following detailed description.

In general, the present invention provides composition boards, comprisedof composition board-forming materials bonded with a thermosetting resinbinder, that have high bond strength and water resistance greater thanthat of boards generally regarded as standards for such compositionboards. characterized in that, prior to applying said thermosettingresin to said composition board-forming materials, said board-formingmaterials are coated with a water-repellent substance and heated to anelevated temperature sufiicient to flux and uniformly distribute saidsubstance on said material.

This invention also provides a method for producing composition boardthat comprises coating composition board-forming material withwater-repellent material; heating at an elevated temperature suflicientto flux and uniformly distribute the water-repellent material on saidcomposition board-forming material; thereby obtaining treatedboard-forming material; admixing treated material with thermosettingresin binder and molding to a composition board; and heat curing saidthermosetting resin binder.

The method of the present invention is broadly applicable to themanufacture of composition board using thermosetting resins andparticulate and/ or fibrous materials. The use of the improved method ofthis invention results in greatly enhanced water resistance of thecomposition board product. Particularly in conjunction with the use of athermosetting resin having a relatively low viscosity, which wouldotherwise penetrate excessively into pores of the particles or fibersand result in a starved (unacceptably weak) glue line, the method of thepresent invention significantly increases the bond strength of thecomposition board produced, as well as enhancing the resistance of thebond against weakening from exposure to water.

The thermosetting resins useful in the method of this invention includeany resins which can be cured, with the application of heat, to a binderwhich is infusible and water-insoluble. As stated hereinbefore,phenol-formaldehyde, urea-formaldehyde and melamine-formaldehyde areexamples of such resins. Also particularly useful in the practice of thepresent invention are ketone-aldehyde resins, e.g., the water-solubleketone-aldehyde resins described in copending application Ser. No.310,920, filed Sept. 23, 1963, resins containing a ketone, an aldehydeand at least one phenolic compound or derivative, e.g., thewater-soluble ketone-aldheyde-phenol resins described in copendingapplication Ser. No. 354,435, filed Mar. 24,

-1964, and resorcinol modified ketone-aldehyde-phenol resins describedin copending application Ser. No. 369,- 008, filed May 20, 1964.

The ketone-aldehyde resins described in Ser. No, 310,- 920 are producedby condensing a ketone reactant and an aldehyde reactant in the presenceof a catalytic amount of ammonia or ammonium hydroxide. The reaction bywhich the water-soluble ketone-aldehyde resins of Ser. No. 310,920 areproduced is a condensation reaction which is catalyzed by either ammoniaor ammonium hydroxide, with the amount of such catalyst used beingbetween about 0.05 mole and about 0.2 mole per mole of ketone reactant.The ketone and aldehyde reactants are reacted under condensationconditions in a ratio of between about one mole and about two moles ofaldehyde reactant per mole of ketone reactant, with a ratio slightly inexcess of one mole of aldehyde per mole of ketone being preferred.

The ketone-aldehyde-phenol resins described in Ser. No. 354,435 areproduced by condensing an aldehyde, a ketone and a phenol inv thepresence of a base capable of catalyzing the condensation reaction. Thereaction by which the water-soluble ketone-aldehyde phenol resins ofSer. No. 354,435 are produced is a condensation reaction conducted inthe presence of a base capable of catalyzing the condensation reaction,and in which the ketone, aldehyde and phenol are reacted in molarproportions of between about 2 and about 8 moles of the aldehyde permole of the phenol and of between about 0.5 and about 2 moles of theketone per mole of the phenol.

The resorcinol modified ketone-aldehyde-phenol resins of Ser. No.369,008 are prepared similarly to those of Ser. No. 354,435, except thatpart of the phenol reactant is replaced with resorcinol. Usually betweenabout one and about 25 mole percent of the total phenolic compounds willbe resorcinol.

The ketone reactant used in preparing the resins of Ser.

Nos. 310,920; 354,435; and 369,008 can be any ketone having at least onehydrogen atom on each carbon atom alpha to the carbonyl group, includingaliphatic (particularly lower alkyl) and cycloaliphatic ketones, e.g.,acetone, methyl ethyl ketone, ethyl ketone, methyl propyl ketones,methyl butyl ketones, ethyl propyl ketones, dihexyl ketones,cyclohexanone, acetonyl acetone, diacetone and mixtures of any of theforegoing ketones. Of the foregoing acetone, methyl ethyl ketone andother ketones having alkyl groups containing up to three carbon atomsattached to the carbonyl group are particularly preferred.

The aldehyde reactant used in the preparation of resins of Ser. Nos.310,920; 354,435; and 369,008 can be any compound having an active groupcharacteristic of the aldheydes, including aliphatic, aromatic andheterocyclic aldehydes, e.g., formaldehyde (including polymeric forms,e.g., paraformaldehyde), acetaldehyde, propionaldehyde, butyraldehyde,acrolein, crotonaldehyde, tiglaldehyde, benzaldehyde, salicylaldehyde,cinnamaldehyde, glyoxal, and mixtures of any of the foregoing aldehydes.Of the foregoing, formaldehyde is a preferred aldehyde reactant.

The phenolic reactant used in the preparation of resins of Ser. Nos.354,435 and 369,008 can be any phenolic compound having hydrogen atomsin at least two and preferably at least three active nuclear positions,including unsubstituted phenol and substituted phenols such asalkylphenols (in which the alkyl groups are preferably lower alkyl),e.g., cresols, xylenols, ethylphenols, propylphenols, butylphenols,amylphenols, phenylphenols, cyclohexylphenols and mixtures of any of theforegoing phenols. Of the foregoing, meta-substituted phenols, variouspara'substituted phenols (e.g., p-arnino phenol), mono-phenols of lowermolecular weight and phenols which are relatively unencumbered againstring reactions are preferred phenolic reactants.

In the manufacture of composition board using any of the aforedescribedthermosetting resins, a solution or slurry containing the resin and athermosetting catalyst are combined with the board-forming particlesand/or fibers. After the combined mass has been molded into a desiredconfiguration, heat and pressure are applied to cure the resin to aninfusible, water-insoluble binder. In general, and particularly withreference to the aforementioned water-soluble ketone-aldehyde andketone-aldehyde-phenol resins, it is most desirable that the viscosityof the resin-containing solution or slurry as applied to theboardforming material should be between about five seconds and aboutnine seconds as measured by the Gardner- Holdt method (ASTM DesignationD154560) at ambient temperature (about 77 F.). Resins having viscositiesbelow five seconds can also be used in accordance with the method ofthis invention to produce composition board characterized by goodresistance to weakening from exposure to water.

In cases wherein the product of the resin-forming condensation reactionhas proper resin concentration and proper viscosity, it can be used inthe manufacture of composition board without further modification. Insuch a case, the resin-synthesis catalyst already present in the productmixture may suffice as the catalyst for the thermosetting reaction.Otherwise, the resin concentration of the solution can be adjusted,e.g., by dilution or evaporation. If desired, the condensation catalystpresent in the resincontaining solution can he neutralized andadditional catalyst or a different catalyst can be used for thethermosetting reaction. With some resins, such as urea-formaldehyde, anacidic thermosetting catalyst, e.g., an ammonium halide or ahydrochloride of a primary, secondary or tertiary amine or of aheterocyclic base, can be used. With many other resins, such as theketone-aldehyde and ketonealdehyde-phenol resins described hereinabove,the thermosetting catalyst is generally a basic compound, such as analkali or alkaline earth metal hydroxide (e.g., NaOH, KOH or Ca(OH) adialkylamine (e.g., dimethylamine or diethylamine), an alkylenediamine(e.g., ethylenediamine), a polyethylene amine (e.g., diethylenetriamineor triethylenediamine) or an alkyleneimine (e.g., pyrroline,pyrrolidine, piperidone or piperazine). The amount of catalyst used tocure the resin is generally between about 0.5 percent and about 12percent, based on the weight of the resin. Generally, about 2 percent issatisfactory.

As mentioned hereinbefore, the composition boards of this inventioninclude particle board and fiber board. They are both prepared by thesame general method of applying the thermosetting resin to the fibers orparticles and then heating the combined mass under pressure. Before theresin is combined with the particulate and/ or fibrous material, themoisture content of the latter should be reduced, if necessary, to alevel which will not excessively inhibit the condensation reaction bywhich curing of the resin occurs.

The level below which the moisture content should be reduced oftendepends on the characteristics of the resin to be used. For example, amoisture level slightly below about 6 percent is desired for curing anacetone-formaldehyde resin of the types described generally hereinbeforeas ketone-aldehyde resins and having a molecular weight of about 400,while a moisture content below amount 8 percent is sufficiently low forcuring a phenol-formaldehyde resin having a molecular weight of about2000. Generally, such a reduction of the moisture content can beaccomplished by drying the particles or fibers at a temperature belowabout 250 F., usually about 220 F., for between about ten minutes andabout 24 hours, depending on their original moisture content and on thecapacity of the dryer used.

In accordance with the method of this invention, the particles or fibersused to make the composition board are treated, prior to theircombination with the thermosetting resin, with a water-repellentsubstance. For example, the particles or fibers can be sprayed with awater-repellent substance such as silicone oils, petroleum oils, or wax.Wax is a preferred water-repellent substance for present purposes, andthe method of treating is hereinafter described in some instances withparticular reference to the use of wax as the water-repellent substance,although the method of this invention is not limited thereto. Treatmentof the particulate or fibrous material with the water-repellentsubstance can be carried out either before, after, or during reductionof the moisture content of the material. However, for reasons explainedhereinafter, it is particularly advantageous to treat the particulateand/ or fibrous material with the water-repellent substance before orduring elevation of the tempertaure of the material for dehydrationpurposes.

When wax is used as the water-repellent substance, the particles orfibers are generally sprayed with a wax-containing emulsion (e.g., anaqueous emulsion) in an amount containing between about 0.25 percent andabout 5 percent wax, based on the weight of the particles or fibers towhich it is added. The preparation of suitable wax emulsions is wellknown to the art and such emulsions are commercially available. Anysuitable type of wax, including those obtainable from petroleum orlignite or by the Fischer-Tropsch synthesis process or from esters ofcarboxylic acids of high molecular weight can be used, but generally apetroleum wax such as a paraffin wax, a microcrystalline wax or slackwax will be used.

In accordance with this invention, the particulate or fibrous materialis heated, following treatment or coating with a normally ,solidwater-repellent substance, to a temperature at which the water-repellentsubstance is sulficiently fluidized for more even distribution on thesurfaces of the particulate or fibrous material, to more effectivelyclose the porous openings of the material against entry of thethermosetting resin to be subsequently applied. The specific temperatureused in such heat-treatment will accordingly depend on a property of thespecific water-repellent substance employed, i.e., the lowesttemperature at which it will melt or soften enough for fluxing and moreeven distribution on the particulate or fibrous material surfaces. Inview thereof, this specific embodiment of the invention broadlyencompasses the use of water-repellent substances which will besufficiently fluidized for such purposes at any temperature which istolerable in the board-forming process, e.g., when cellulosicboard-forming material is being used, any temperature up to thattemperature (about 450 F.) at which the cellulosic board-formingmaterial would be caused to char. For convenience, there will generallybe used a Water-repellent substance having a melting or softening pointbetween about 120 F. and about 200 F. In general, however,petroleum-derived microcrystalline waxes have coagulation temperaturesin the range of from about 120 F. to about 200 F., and parafiin waxeshave coagulation temperatures in the range of from about F. to about 200F.

It will be seen that the temperatures necessary for heatfluxing many ofthe waxes useful in the method of this invention are lower thantemperatures identified hereinbefore as suitable for drying of theparticulate and/or fibrous material usually necessary before addition ofthe resin. Accordingly, heat-fluxing of the water-repellent substance onthe surfaces of the particles and/or fibers can be advantageouslyaccomplished by treating the particles with the water-repellentsubstance either prior to or during elevation of their temperature fordehydration purposes, with heat-fiuxing of the wax and drying of theparticles and/or fibers thereafter taking place wholly or partlysimultaneously. For example, fibers or chips can be dried to a moisturelevel above that ultimately desired, and while the chips are attheelevated drying temperature, the wax can be applied thereto in the formof an aqueous solution or emulsion (temporarily raising the moisturelevel of the chip-containing mass); thereafter, continued heating of themass at the elevated drying temperature (up to 250 F., usually about 220P.) will simultaneously flux the wax on the surfaces of the particlesand complete the reduction of the moisture content of the mass to thelevel desired below about 6 percent, prior to the addition of thethermosetting resin.

In another embodiment of the invention, the particulate or fibrousboard-forming material is treated with a waterrepellent substance andwith a resin curing catalyst prior to combination of the board-formingmaterial with a thermosetting resin. This embodiment has the advantagethat, since the resin curing catalyst is combined with the board-formingmaterial prior to addition of thermosetting resin thereto, the resin andthe catalyst do not contact each other sooner than is necessary in theboardforming process. Accordingly, the danger that the catalyst couldcause premature setting of the resin before it is combined with theparticles or fibers, as sometimes happens in the heretofore customarypractice of combining the 'resin and the catalyst prior to theiraddition to the boardforming material, is avoided in this embodiment.The resin curing catalyst can be applied to the particles or fibers inthis embodiment either before or following their treatment with awater-repellent substance, or it can be applied as a constituent of theemulsion containing the Water-repellent substance. If it is appliedfollowing treatment of the board-forming material with a water-repellentsubstance, the resin curing catalyst can be applied in this embodimenteither before, during or following heattreatment of the water-repellentsubstance to improve its distribution on the surfaces of the particlesor fibers. In one specific embodiment, the water-repellent substance andresin curing catalyst are combined in an emulsion which is sprayed onfibers or particles which are partially dried, after which furtherheating improves the distribution of the water-repellent substance andcompletes drying of the mixture to the desired moisture level, while thecatalyst is retained on the surfaces of the dried fibers or particles.

Following preparation of particulate or fibrous material according tothe aforedescribed method, it is combined with a thermosetting resinand, if it is not already present in the particle or fiber-containingmass, at curing catalyst. The resin-coated particles or fibers are thengenerally placed in a molding press in which they are molded into acompact mass of desired size and shape by the application of heat andpressure. The compactness, density and hardness of the product particleboard or fiber board is governed to a great extent by the amount ofpressure used. In general, pressure between about 50 p.s.i. and 800p.s.i. are employed. Molding is usually carried out at temperaturesbetween about 300 F. and about 425 F. If the board contains cellulosicmaterial, the molding temperature should not exceed temperatures in theorder of about 450 F above which charting may occur. The preferredmolding time will be dependent upon the temperature and the flowcharacteristics of the resin being cured. Time should be allowed topermit the resin to be distributed evenly and to cure sufliciently toprovide a board of substantially uniform strength. The period of timecan be between about 3 minutes and about 1 hour. In general practice,molding time will be between about minutes and about minutes.

The amount of resin applied to the fibrous and/ or particulate materialto make the composition board should be sufficient that the finishedboard will contain, by weight, between about 2 percent and about 30percent of thermoset resin. If desired, e.g., for economic reasons,resins generally used in manufacture of the composition board of thisinvention can be extended by adding a filler thereto prior to thethermosetting step. Fillers suitable for this purpose, including clay,wood flour, soya flour and dried blood, can be added in relatively largeproportion without impairment of the properties of high bond strengthand resistance to bond weakening from the action of water whichcharacterize the composition board produced by the method of thisinvention.

The following examples are for the purpose of illustrating thepreparation of the composition board of this invention. It will beunderstood that this invention is not limited to the specificboard-forming materials, resins, water-repellent substances or catalystsused in the examples, or to the particular operations and manipulationsinvolved. Other board components, as exemplified thereinbefore, andother board-forming techniques can be employed within the scope of thepresent invention, as those skilled in the art will readily appreciate.

Example 1 Eleven hundred and sixty grams of acetone, 810 g. formaldehydesolution (37% CH O) and 310 g. paraformaldehyde (95% CH O) were chargedto a stirred autoclave. The mixture was heated to 140 F. and 50 ml. ofaqueous ammonium hydroxide (28% NH was added carefully through apressurized buret. The temperature was raised to 255-260" F. and heldfor 2 hours. The highest recorded pressure was 100 p.s.i. The autoclavewas cooled to room temperature and the contents were distilled torecover 50% unreacted acetone. The resultant solution contained 50%resin solids.

A particle board was prepared using an acetone-formaldehyde resinproduced as aforedescribed and having a viscosity (Gardner-Holdt) of 3.4seconds. The particle board was prepared by spraying aspen wood flakeswith paraffin wax emulsion, in an amount of 1% wax, based on the weightof finished board, and with the resin solution (also containing 8 weightpercent diethylenetriamine) in an amount of 7% resin, also based uponthe weight of finished board. The sprayed wood flakes were matted in aforming bin and hot pressed to effect curing, for 15 minutes underpressure suflicient to produce a /2" board. The curing temperature was350 F. Pertinent data and test results (ASTM Designation: D1037-60T) forwater absorption and for tensile strength perpendicular to the surface(measuring internal bond strength) are set forth in Table I. Commercialstandards are included for comparison.

Example 2 A particle board was prepared, using an acetone-formaldehyderesin produced as described in Example 1, having a viscosity(Gardner-Holdt) of 3.7 seconds. The particle board was prepared byspraying aspen wood flakes with paraflin wax emulsion, in an amountsufficient to deposit about one percent wax, based on the weight of theflakes. The flakes were then dried at 220 F. to a moisture content ofbelow 6 percent. The treated flakes were then sprayed with theresin-containing solution (also containing 8 percent diethylenetriaminecatalyst) in an amount of 7% resin, based upon the weight of finishedboard. The sprayed treated wood flakes were matted in a forming bin andhot pressed to effect curing, for 15 minutes under pressure suflicientto produce a /2" board. The curing temperature was 350 F. Pertinent dataand test results (ASTM Designation: D1037-60T) for water absorption andfor tensile strength perpendicular to the surface (measuring internalbond strength) are set forth in Table I. Commercial standards areincluded for comparison.

Example 3 A particle board was prepared as described in Example 2,except that a resin, produced as in Example 1 and having a Gardner-Holdtviscosity of 6.0 seconds (415 cs.), was used' Pertinent data and testresults for the finished board (ASTM Designation: Dl037-60T) for waterabsorption and for tensile strength perpendicular to the surface(measuring internal bond strength) are set forth in Table I. Commercialstandards are included for comparison.

Example 4 A particle board was prepared, using an acetone-formaldehyderesin produced as described in Example 1 and having a viscosity(Gardner-Holdt) of 7.5 seconds. The particle board was prepared byspraying aspen wood flakes with paraffin wax emulsion in an amountsufficient to deposit about one-half percent wax, based upon the weightof the flakes. The flakes were then dried at 220 F. to a moisturecontent of below 6 percent. The treated flakes were then sprayed withthe resin-containing solution (also containing 8 weight percentdiethylenetriamine catalyst) in an amount of 7% resin, based upon theweight of finished board. The sprayed, treated wood flakes were mattedin a forming bin and hot pressed to effect curing, for 15 minutes underpressure sutficient to produce a /2" board. The curing temperature was400 F. Pertinent data and test results (ASTM Designation: D1037-60T) forwater absorption and for tensile strength perpendicular to the surface(measuring internal bond staength) are set forth in Table I. Commercialstandards are included for comparison.

Example 5 A particle board was prepared, using an acetone-formaldehyderesin produced as described in Example 1 and having a viscosity(Gardner-Holdt) of 9 seconds. The particle board was prepared byspraying aspen wood flakes with paraflin wax emulsion, in an amountsuflicient to deposit about three percent Wax, based upon the weight ofthe flakes. The flakes were then dried at 220 F. to a moisture contentof below 6 percent. The treated flakes were then sprayed with theresincontaining solution (also containing 8 percent diethylenetriaminecatalyst) in an amount of 7% resin, based upon the weight of finishedboard. The sprayed, treated wood flakes were matted in a forming bin andhot pressed to effect curing, for 15 minutes under pressure suflicientto produce a /2 board. The curing temperature Was 400 F. Pertinent dataand test results (ASTM Designation: D1037-60T) for water absorption andtensile strength perpendicular to the surface (measuring internal bondstrength) are set forth in Table I. Commercial standards are includedfor comparison.

1 Standard practice, not a commercial requirement.

From the data in Table I, it will be noted that a board prepared bystandard methods with a low-viscosity resin (Example 1) has a lowresistance to absorption of water and substandard bond strength. On theother hand, boards prepared with a resin of similarly low viscosity, butin accordance with the method of this invention (Example 2), hasenhanced resistance to absorption of water and excellent bond strength.With the use of a resin of ordinarily sufficient viscosity (5 or moreseconds), boards prepared in accordance with the method of thisinvention have even higher bond strength and good resistance toabsorption of water, as Examples 3, 4, and 5 demonstrate.

Example 6 Aparticle board was prepared, using anacetone-phenolformaldehyde resin of the type described in copendingapplication Ser. No. 354,435 and having a viscosity (Gardner-Holdt) of4.8 seconds. The particle board was prepared by spraying aspen woodflakes with a heavy refined paraffin oil (Nujol) in an amount suflicientto deposit about three percent oil, based on the weight of the flakes.The sprayed flakes were dried at 2 F. for 16 hours and then sprayed withthe acetone-phenol-formaldehyde resin-containing solution (alsocontaining 8 percent diethylenetriamine catalyst) in an amount of 7percent resin, based on the weight of the finished board. The resin andoil-treated flakes were matted in a forming bin and hot pressed toeflect curing, for 8 minutes under pressure which produced a board of0.49 inch thickness. The curing temperature was 350 F. Pertinent dataand test results (ASTM Designation: Dl037-60T) for water absorption andfor tensile strength perpendicular to the surface (measuring internalbond strength) are set forth in Table II.

. Example 7 A particle board was prepared, using an acetone-phenolformaldehyde resin of the type described in copending application Ser.No. 354,435, and having a viscosity (Gardner-Holdt) of 5.2 seconds. Theparticle board was prepared by spraying aspen wood flakes with paraffinwax emulsion also containing suflicient diethylenetriamine resin-curingcatalyst to deposit on the flakes an amount of the catalyst equal to 8%of the combined weight of the catalyst and the resin subsequentlyapplied. The mixture of flakes, wax and resin-setting catalyst was driedat 220 F. for 16 hours, and then sprayed with theacetonephenol-formaldehyde resin-containing solution in an amount of 7%resin, based on the weight of the finished board. The resin and flakeswere matted in a forming bin and hot pressed for 8 minutes at 350 F. toeffect curing. Pertinent data and test results (ASTM DesignationD1037-60T) for water absorption and for tensile strength perpendicularto the surface (measuring internal bond strength) are set forth in TableII.

From the data in Table II, it can be seen that boards prepared byembodiments of the method of this invention, wherein a mineral oil isthe water-repellent substance (Example 6) and the board-forming materialis treated with a water-repellent substance and with a resin-settingcatalyst prior to combining the board-forming material with the resin(Example 7), were characterized by good internal bond strength.

Example 8 A particle board was prepared, using an acetoneformaldehy'deresin produced as described in Example 1 and having a viscosity(Gardner-Holdt) of 5.0 seconds. The particle board was prepared bydrying aspen wood flakes (originally containing 108% moisture, based onweight of dry wood content) in a tumbling drum dryer at a temperature of220 F. until the moisture content was reduced to 24% (dry wood basis).While the chips were still at the drying temperature of 220 F., theywere sprayed with an aqueous emulsion containing 1% of parfiin wax in anamount suflicient to deposit 0.5 wax, based on the weight of the flakes.Drying of the mixture of wax and flakes was continued in the tumblingdrum dryer at 220 F. until moisture content of the mixture was reducedto 2% (dry wood basis). The treated flakes were then sprayed with theacetone-formaldehyde resincontaining solution (also containing 8 weightpercent diethylenetriamine catalyst) in an amount of 7% resin, based onthe weight of the finished board. The resin and wax-treated wood flakeswere matted in a forming bin and hot pressed to effect curing for 15minutes under pressure which produced a board of 0.47 inch thickness.The curing temperature was 400 F. Pertinent data and test results (ASTMDesignation: D1037-60T) for water absorption and for tensile strengthperpendicular to the surface (measuring internal bond strength) are setforth in Table III.

Example 9 A particle board was prepared, using anacetonephenol-formaldehyde resin of the type described in copendingapplication Ser. No. 354,435 and having a viscosity (Gardner-Holdt) of5.0 seconds. The particle board was prepared by drying aspen wood flakes(originally containing moisture, based on weight of dry wood content) ina tumbling drum dryer at a temperature of 220 F. until the moisturecontent was reduced to 24% (dry wood basis). While the chips were stillat the drying temperature of 220 F., they were sprayed with an aqueousemulsion containing 1% paraffin wax in an amount sufficient to depositt0.5% wax, based on the weight of the flakes. Drying of the mixture ofWax and flakes was continued in the tumbling drum dryer at 220 F., untilmoisture content of the mixture was reduced to 2% (dry wood basis). Thetreated flakes were then sprayed with the acetone-phenol-formaldehyderesincontaining solution (also containing 8 weight percentdiethylenetriamine catalyst) in an amount of 7% resin, based on theweight of the finished board. The resin and wax-treated wood flakes werematted in a forming bin and hot pressed to effect curing, for 6.5minutes under pressure which produced a board of 0.49 inch thickness.The curing temperature was 400 F. Pertinent data and test results (ASTMDesignation Dl03762T) for Water absorption, Modulus of Rupture (MOlR),and for tensile strength perpendicular to the surface (measuringinternal bond strength) are set forth in Table III.

TABLE III Example Density, #/it. Water absorption, Wt. gain, percent.

psi. for five minutes and then hot pressed at 300 F. for 8 minutes. Theresulting board was conditioned to 68:6 F. and 65:2% relative humidityand tested according to ASTM Dl03762T. Pertinent data are set 12.0 15.5Thickness swelling, percent I 5 forth In Table IV. fiigei-inal bond,p.s.1 Example 11 4-H0ui' satires? u gfalteliAbs(p.,l})erccnt This boardwas made by the identical procedure as ff gf g fgf 91 98 used in Exampleexcept that a phenol-formaldehyde fiw g ig k i I t 100 105 10 resin wasused. The resin contained 40% solids. Because g gg 2283 551: 27 g, ofresin dilution five-minute drying of the matte (in the Internal Bond,p.s.i s0 87 tumbling drum) was required in order to eliminate excess Inthe 4-Hour Boil Test, a board specimen is placed in Water beforehotopressmg'. The board was H for boiling water for 4 hours andoven-dried for 20 hours at 48 hours at f i i hot stackmg' Pertinent 140F. Then, it is retested for internal bond strength. data are Set on m ae In the 6-Day Cycle Boil, a board specimen is run Example 12 throughsix boiling and drying cycles of the 4-Hour Boil Eleven hundred (1100)grams of ground Whole bagasse g zz i iggg zg g last zo'hour dryingtested for (at 6-10% moisture content) was charged into the tumblingdrum mixer. The oven dry weight of the bagasse From the data 1n TableIII 1t w1ll be noted that boards was about 1040 grams. The atomizmgnozzle was used re ared with a ketone-aldeh de resin Exam 1e 8 and 31111 a ketone-aldehyde-phen l resin Examp ie 9) and to apply 424 grar-ns ofwater (40% by Welght) g if in accordance with an embodiment of. themethod of this gi r ii g i z rgz g gi 32 invention wherein awater-repellent substance is comweighogwere a'pplied by 'atognizingnozzle as a 5% wax bined with the board-forming material duringelevation of its temperature above the melting temperature of the ig ggi g gzg giz i gglg g i gfi ig fgg: water-repellent substance werecharacterized by very four (94) grams of phenol-formaldehyde resin (9%by Eg s 32 Strength and excellent reslstance to absorpuon weight) wereapplied as received as a 40% solution. Five- Bagasse board The followingexamples demonstrate mmute drymg 5 the matlt? (In the tumbling grequired in or er to e lmmate excess Water. ate g:5 :5 gi gg fi g fsfi z582 ig g glf moisture was determined and 990 grams of the treated tiO IlEII meth d oi aPPlying wZx to i he fibers was eii bagasse i gg formedas a 12 X E L onto a stee can p ate. e matte was pre-presse co plo ed.In the remaimn exam les, the method of this ine ven t ion was used topre ireat tlie whole bagasse with wax. 583 3 $2,3 fi gf z i g ii Inpreparing the boards of the examples Conventiona cured at 210 F for 48hours to simulate hot stacking g s"g g gfig i gg i g ggi'ig ig g g Theboard was conditioned at 68i6 F. and 65- *-2% r S P e rm 6 Y 6 RH. andtested according to ASTM Method D1037-62T. resms' Pertinent data are setforth in Table IV.

Exam le 10 p Examples 13 through 16 Eleven hundred (1100) grams ofground whole bagasse Boards were made with commercial phenol formal at6-107 moisture content was char ed into th e t umbling di um mixer. Theoven dry Weight o f the bagass: dghyde resms ur-lder menu-Cal condmonsas Example was about 1040 grams The atomizing nozzle was used wlth thefollowmg exceptions: bOa-rd denslty (2) to pp y 104 grams net Waxemulsion y press cycle and (3) amount at resln solids used. Board rrties are re orted in Ta e IV. weight) onto the bagasse fiber wh1le thefiber was being p ope p rotated in the tumbling drum. The atomi zingnozzle was Examples 17 h h 22 then used to apply 94 grams of solidsurea-formal- 50 dehyde resin (9% by weight) while the fiber was beingBoards were made with acetone-phenolformaldehyde rotated in the tumblingdrum. Matte moisture was deterresin prepared as described in Ser. No.354,435, having mined and 990 grams of the treated bagasse fiber was aGardner-Holt viscosity of 6, with similar process manaully formed as a12 x 18" matte onto a steel caul variations as stated above. Board roerties are re orted P P P plate. The matte was pre-pressed (coldpressed) at 200 50 in Table IV.

TABLE IV Example N0 10 11 12 13 14 15 16 17 1s 19 20 21 22 Resin Solids,percent 9 9 9 9 9 9 9 9 9 9 7 9 9 IgressdCgcle: t F./min 300/8 350/8400/10 350/10 350/05 400/10 400/05 450/10 400/10 400/05 350/05 400 10400 115 Densitg #um 40 45 40 42 37 4s 43 40 40 3s 43 4s 4s T hi ekr s,in .421 .552 .423 .5 2 .433 .4951

er S I 81'0811 a .4 2 T ickness i /e11 percent. 30 21 16 14 21 13 6 1O10 11 16 14 14 Internal Bond, p.s.i 67 37 54 02 49 95 125 70 03 73 71111 112 MOR,p.s.i.... 2, 530 2, 052 2,332 2, 540 1,000 4,171 3,407 2,0132, 709 1, 088 2,571 4, 050 3,812 4HM.Bp, i.i 207 244 270 330 207 402 400204 320 278 327 539 427 1'. 011 Water'Absorp, percent 110 111 93 160 9170 73 95 113 97 52 M Thickness Swell, percent. 38 36 35 39 25 12 19 3922 52 29 28 6 D Internal 1133mm, p.s.i 23 40 57 31 96 54 53 48 41 87 aCO 0 View Absorp., percent.-- 140 100 01 142 94 77 s3 85 103 103 85Thickness Swell, percent. 0) 63 38 34 47 27 10 22 22 23 56 32 34Internal bond, p.s.i (I) 11 50 56 2t) 45 54 48 27 47 65 1 No test.

Although the present invention has been described with preferredembodiments, it is to be understood that modifications and variationsmay be resorted to, without departing from the spirit and scope of thisinvention, as those skilled in the art, will readily understand. Suchvariations and modifications are considered to be within the purview andscope of the appended claims.

What is claimed is:

1. In a method for producing composition board comprising combiningcomposition board-forming material with a thermosetting resin, moldingthe board-forming material, and curing said resin, the improvement thatcomprises pretreating the board-forming material with a water-repellentsubstance selected from the group consisting of silicone oils, petroleumoils, and water-insoluble wax and heating at an elevated temperaturebelow about 250 F. for between about minutes and about 24 hours to fluxand uniformly distribute said substance on said material.

2. A method, as defined in claim 1, in which said compositionboard-forming material comprises cellulosic material.

3. A method, as defined in claim 2, in which said thermosetting resincomprises the product obtained by reacting a ketone having at least onehydrogen atom on each carbon atom alpha to the carbonyl group, analdehyde, and a phenolic compound in the presence of a base.

4. A method, as defined in claim 3, in which said water-repellentsubstance is a water-insoluble wax.

5. A method, as defined in claim 2, in which said water-repellentsubstance is water-insoluble wax.

6. A method, as defined in claim 4, in which said cellulosic material iswhole, un-depithed bagasse.

7. A method, as defined in claim 5, in which said cellulosic material iswhole, un-depithed bagasse.

8. The composition board produced by the method defined in claim 6.

9. Composition board, as defined in claim 8, in which said compositionboard-forming material comprises cellulosic material.

10. Composition board, as defined in claim 9, in which saidthermosetting resin comprises the: product obtained by reacting a ketonehaving at least one hydrogen atom on each carbon atom alpha to thecarbonyl group, an aldehyde and a phenolic compound in the presence of abase.

11. Composition board, as defined in claim 10, in which saidwater-repellent substance comprises a waterinsoluble wax.

12. Composition board, as defined in claim 11, in which said cellulosicmaterial is whole, un-depithed bag-asse.

References Cited UNITED STATES PATENTS 2,962,459 11/1960 Ash et al.260-17.2 3,006,883 10/ 196 1 Cambron 260 3,023,136 2/1962 \Himmelhe'beret al. 26017.2 3,133,031 5/1964 Maxwell et al. 260--17.3 3,152,94010/1964 Abel et al. 156-457 FOREIGN PATENTS 655,689 8/1951 GreatBritain.

WILLIAM H. SHORT, Primary Examiner.

E. M. WOODBERRY, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,410,813 November 12, 1968 Craig C. Campbell et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 9, line 42, "2 F." should read 220 F. Column 14, line 4, "Claim6" should read Claim 1 Signed and sealed this 10th day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer WILLIAM E. SCHUYLER, JR.

Commissioner of Patents

